The 1931 Model 370A V-12 was introduced in October 1930. A V-12 roadster was used as the pace car at the Indianapolis 500. The Cadillac V-12 had a shorter wheelbase than the Cadillac V-16, with a choice of 140 in (3,556 mm) or 143 in (3,632 mm), compared to the V-16's 148 in (3,759 mm), but it offered a similar choice of Fisher and Fleetwood semi-custom bodies. It was difficult to tell a Cadillac V-12 from a Cadillac V-16 unless you were close enough to read the figure "12" mounted on the headlight tie bar, but the hood was four inches (102 mm) shorter, and the headlights and horns smaller than a V-16's. More significantly, the V-12 cost about $2,000 less for each bodystyle, starting at $3,795. The Cadillac V-12 might have been lower in prestige than the Cadillac V-16, but it joined a select group of 1930s cars with multicylinder engines, namely those manufactured by Franklin, Hispano-Suiza, Horch, Lagonda, Maybach, Packard, Rolls-Royce, Tatra, Voisin, Walter, Marmon and Lincoln. Moreover, thanks to its lower price, it immediately outsold the Cadillac V-16 with 5,733 sold in the 1931 model year, versus a mere 363 for the V-16.

The appearance of the 1932 Series 370B benefited from a radiator shell that flared on the top, more flaring fenders and curved running boards. Mechanical changes included a stiffer frame, and a Cuno self-cleaning oil filter mounted at the right hand side of the clutch housing. Dual Detroit Lubricator carburetors were used in place of the Cadillac/Johnson carburetors that had been standard equipment on Cadillacs for 20 years. Largely thanks to the deepening Great Depression sales plunged to 1740 units.

Styling changes to the 1933 Series 370C included a V-shaped grill that blended into the painted radiator shell, a radiator cap hidden under the hood, and skirts on the front and rear fenders for a more streamlined look.Fisher no-draft individually controlled vent windows were a new standard feature. Sales fell further to 953 cars.

The 1934 Series 370D was restyled yet again but this time was mounted on a completely new chassis. The radiator grill slanted rearward with a central bar and five horizontal sections, the windshield sloped even more rearward, headlights were enclosed in new teardrop housings mounted on streamlined supports, the horns joined the radiator cap under the hood, the spare tire was concealed under a new beaver tail deck on most models and the whole car sat approximately 2 inches (51 mm) lower. Significant mechanical advancements included dual X-frame chassis construction, "Knee-Action" front coil spring suspension that greatly reduced unsprung weight and Hotchkiss steering. The 1935 Series 370E saw the addition of the Fisher Turret Top on Fisher bodied cars and an increase in horsepower to 150. Sales over the two years combined totaled only 1098.